Field of the Invention
This invention relates generally to vehicle systems and navigation processes, such as railway systems including trains travelling in a track or rail network, and in particular to a train navigation system and method that provide improved navigation in railway networks, such as in connection with push-pull train configurations, commuter train applications, and the like.
Description of Related Art
Vehicle systems and networks exist throughout the world, and, at any point in time, a multitude of vehicles, such as cars, trucks, buses, trains, and the like, are travelling throughout the system and network. With specific reference to trains travelling in a track network, the locomotives of such trains are typically equipped with or operated using train control, communication, and management systems (e.g., positive train control (PTC) systems), such as the I-ETMS® of Wabtec Corp. In order to effectively manage all of the trains, navigation systems and processes are implemented, both at the train level and the central dispatch level. For example, many PTC systems rely on navigation systems and processes to determine on which track the train is operating, and to determine where the train will be operating in its route ahead. Such navigation generally relates to two modes, i.e., initial location determination and route navigation.
With respect to the difficulties in initial location determination, there are existing methods and arrangements that are in use, such as transponders on one or more of the railroad cars (or the locomotives) of the train, track circuits, forward-looking vehicle cameras, and/or crew interaction. With the exception of crew interaction, the remaining methods and arrangements require the installation and use of additional hardware that is relatively costly and requires ongoing maintenance. Although crew interaction does not require additional hardware (beyond the typically-installed cab interface in PTC systems), there remains the undesired aspect of relying on human input in a safety critical system. In existing PTC systems, the need for initial location determination occurs whenever a system is initialized, and in push-pull commuter operations where initialization would occur each time the crew swapped cabs to run in the other direction. The frequency of need for determining initial location, and the drawbacks of cost or potential for error with existing systems, warrant the need from an improved method and system.
With respect to the difficulties in route navigation, there exist certain methods and arrangements that are in use, e.g., transponders, switch position monitors, GPS path tracking, and/or crew interaction. For predictive enforcement of conditions ahead of the train, the use of a switch position monitoring method is beneficial since it permits the PTC system to determine where the train will be prior to traversing a switch with a diverging route. There are, however, other cases where predictive enforcement is not required, but determination of the route being taken is still desirable. For example, such a case arises in relation to the operation in passenger terminal areas that are excluded from compliance with PTC requirements. Such terminal areas often have multiple parallel tracks with numerous switches. A further challenge in these areas relates to the fact that the GPS path tracking may prove unreliable due to building obstructions or underground operation. Equipping all switches in a terminal area with tracking functionality would be costly, as would the installation of transponder equipment. Further, GPS tracking would be unreliable, and crew interaction is undesirable (as discussed above) due to the workload on the crew to make selections, and the large number of switches that are normally traversed in a large terminal area. For at least these reasons, there is a need in the art for an improved route navigation method and system.